System and method for performing ablation using a balloon

ABSTRACT

An apparatus comprises a catheter, a conductive element and a balloon. The catheter has a lumen. The conductive element is disposed along the catheter. The balloon has an interior in fluid communication with the lumen of the catheter. The balloon is formed of a conductive material conductively coupled to the conductive element. The balloon has a collapsed configuration and an expanded configuration.

BACKGROUND

The invention relates generally to systems and methods for performingablation. More specifically, the invention relates to a system andmethod for performing ablation using a balloon, for example, in apreviously formed tissue cavity.

Various known techniques exist for treating residual tumor tissuefollowing the gross removal of the tumor. Such post-operative treatmentsinclude, for example, radiation techniques and brachytherapy techniques.

These post-operative treatments suffer various shortcomings. Forexample, radiation techniques use common equipment that involvesignificant logistical challenges. In addition, radiation techniques arecostly and time consuming. Radiation techniques typically involvemultiple treatments over weeks and sometimes months. In addition,radiation often results in unintended damage to the tissue outside thetarget zone. In other words, rather than affecting the likely residualtissue, typically near the original tumor location, radiation techniquesoften adversely affect healthy tissue. Alternative focused-radiationtherapy typically involves costly equipment with limited availability.

Standard brachytherapy techniques typically require simultaneousplacement of numerous catheters in the tumor and surrounding tissue withindividual radioactive sources. Placement of these catheters can becostly, cumbersome and time consuming.

Thus, a need exists for an improved system and method for treatingresidual tumor tissue following the gross removal of the tumor.

SUMMARY OF THE INVENTION

An apparatus comprises a catheter, a conductive element and a balloon.The catheter has a lumen. The conductive element is disposed along thecatheter. The balloon has an interior in fluid communication with thelumen of the catheter. The balloon is formed of a conductive materialconductively coupled to the conductive element. The balloon has acollapsed configuration and an expanded configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a side view of a balloon catheter in an expandedconfiguration, according to an embodiment of the invention.

FIG. 2 depicts a cross-sectional view of the balloon catheter of FIG. 1taken along line 2-2 of FIG. 1.

FIG. 3 shows a cross-sectional view of the balloon catheter shown inFIGS. 1 and 2 while in a collapsed configuration.

FIG. 4 illustrates a cross-sectional view of the balloon catheter shownin FIGS. 1 and 2 while in the expanded configuration and while disposedwithin a previously formed tissue cavity.

FIG. 5 shows a side view of a balloon catheter according to anotherembodiment of the invention.

FIG. 6 shows a cross sectional view of the balloon catheter of FIG. 5taken along line 6-6 of FIG. 5.

FIG. 7 shows a cross-sectional view of a multi-layer balloon of aballoon catheter while in an expanded configuration, according toanother embodiment of the invention.

FIG. 8 shows a cross-sectional view of a multi-layer balloon of aballoon catheter while in an expanded configuration, according to yetanother embodiment of the invention.

FIG. 9 depicts a cross-sectional view of a balloon catheter having amulti-lumen catheter, according to yet another embodiment of theinvention.

FIG. 10 shows a cross-sectional view of a balloon catheter having amulti-lumen catheter, according to yet another embodiment of theinvention.

FIG. 11 illustrates a cross-sectional view of a balloon catheter havingmultiple concentric balloons, according to an embodiment of theinvention.

FIG. 12 depicts a partial cross-sectional view of a balloon catheterhaving multiple concentric balloons, according to another embodiment ofthe invention.

FIG. 13 depicts a side view of a balloon catheter having an atraumatictip, according to an embodiment of the invention.

FIG. 14 depicts a block diagram of an ablation system having a ballooncatheter, according to an embodiment of the invention.

FIG. 15 is a flow chart illustrating a method for making a balloonaccording to an embodiment of the invention.

FIG. 16 shows a cross-sectional view of a balloon catheter in anexpanded configuration, according to another embodiment of theinvention.

DETAILED DESCRIPTION

Once a tumor has been removed, a tissue cavity remains. The tissuesurrounding this cavity is the location within the patient where areoccurrence of the tumor may most likely occur. Consequently, after atumor has been removed, it is desirable to destroy the surroundingtissue (also referred herein as the “margin tissue”). Variousembodiments described herein relate to balloon catheter devices andmethods for ablating, for example, the margin tissue associated with atissue cavity formed by the removal of a tumor.

In one embodiment, an apparatus comprises a catheter, a conductiveelement and a balloon. The catheter has a lumen. The conductive elementis disposed along the catheter. The balloon has an interior in fluidcommunication with the lumen of the catheter. The balloon is formed of aconductive material conductively coupled to the conductive element. Theballoon has a collapsed configuration and an expanded configuration.

The balloon has the collapsed configuration, for example, when theballoon is exterior to a patient's body or being percutaneously disposedinto the previously formed tissue cavity. The balloon in the collapsedconfiguration has a smaller size or volume than when the balloon is inthe expanded configuration. The balloon has the expanded configuration,for example, when the balloon is disposed within the previously formedtissue cavity for ablation. In general, the balloon has a range ofpossible configurations, which include the collapsed configuration(typically at its smallest size or volume) and the expandedconfiguration corresponding to the size of the tissue cavity.

The balloon is constructed to be electrically conductive, or to haveelectrically conductive portions. The electrical conductivity can beachieved by forming all or part of the body of the balloon fromelectrically conductive material (such as for example, a conductivepolymer or a non-conductive material that incorporates conductiveelements such as metallic particles or other metallic elements) with aconductive layer or coating, such as a conductive ink, or withconductive elements attached to the balloon. In embodiments of theballoon where the conductive material is formed from a conductivepolymer, the balloon can be formed, for example, using photolithographytechniques. In embodiments of the balloon where the conductive materialhas a specific shape, the conductive material of the balloon can beformed from, for example, metallic stampings, wires or machined shapes.The term “electrically conductive” is used herein to mean the propertyof a material or medium permitting flow of electricity through itsvolume for the conditions to which it is normally subjected. In otherwords, although all materials and mediums are electrically conductive tosome extent, electrically conductive materials or mediums consideredherein exclude materials or mediums that are electrically conductiveonly at levels that are uncharacteristically high for typical ablationdevices.

FIG. 1 depicts a side view of a balloon catheter in an expandedconfiguration, according to an embodiment of the invention. Ballooncatheter 100 includes a catheter 110, a balloon 120 and a conductiveelement 130 (e.g., a conductive wire covered with insulation). FIG. 2shows a cross-sectional view of balloon catheter 100 while in theexpanded configuration. As shown in FIG. 2, catheter 110 includes alumen 112 and balloon 120 defines an interior 125.

FIG. 3 shows a cross-sectional view of the balloon catheter shown inFIGS. 1 and 2 while the balloon catheter is in a collapsedconfiguration. The balloon catheter 100 can be changed from a collapsedconfiguration to an expanded configuration by introducing a fluid intolumen 112. As the fluid traverses lumen 112, it can then fill theballoon cavity 125 thereby expanding balloon 120 into its expandedconfiguration. The fluid can be, for example, a liquid such as water ora saline solution, or can be a gas, such as air. Although the conductiveelement 130 is shown in FIG. 1 as being disposed along and on thecatheter 110, in alternative embodiments the conductive element 130 isdisposed along the catheter 110 and within the lumen 112.

Balloon 120 can be formed, for example, of a conductive material or of anon-conductive material with conductive material uniformly distributedthroughout balloon 120. Such conductive material can be electricallycoupled to conductive element 130 thereby allowing energy, such asradiofrequency (RF) energy, to be transferred from conductive element130 to the conductive material of balloon 120. Such RF energy can beprovided by an RF generator (not shown in FIGS. 1 through 3) coupled toconductive element 130. Balloon catheter 100 can operate as a monopolardevice where the other pole (not shown) is disposed on the patient.

FIG. 4 illustrates a cross-sectional view of the balloon catheter shownin FIGS. 1 and 2 while in the expanded configuration and while disposedwithin a previously formed tissue cavity. As shown in FIG. 4, balloon100 is in the expanded configuration such that balloon 120 expands tofill the previously formed tissue cavity. The previously formed tissuecavity is surrounded by margin tissue 10. As the balloon catheter isactivated, the balloon catheter defines a kill zone 20 within which themargin tissue 10 is destroyed through ablation.

FIG. 5 shows a side view of a balloon catheter according to anotherembodiment of the invention. Balloon catheter 500 includes catheter 510,balloon 520 and conductive element 530. Balloon catheter includes aconductive material integrally formed with balloon 520 such that theconductive material is arranged in paths referred to herein asconductive portions 521. FIG. 6 shows a cross-sectional view of ballooncatheter 500 shown in FIG. 5. As FIG. 6 shows, balloon 520 includesconductive portions 521 and non-conductive portions 522. Ballooncatheter 520 defines an interior 525. Balloon catheter 500 can operateas a monopolar device where the other pole (not shown) is disposed onthe patient.

FIG. 7 shows a cross-sectional view of a multi-layer balloon of aballoon catheter while in an expanded configuration, according toanother embodiment of the invention. More particularly, multi-layerballoon 720 includes two concentric balloon portions 723 and 727. Innerballoon 723 includes conductive portions 721 and non-conductive portions722. Similarly, outer balloon 727 includes conductive portions 728 andnon-conductive portions 729. Inner balloon portion 723 and outer balloonportion 727 are arranged such that the conductive portions 721 of innerballoon portion 723 are aligned with the non-conductive portions 729 ofouter balloon 727. Similarly, the non-conductive portions 722 of innerballoon 723 are aligned with the conductive portions 728 of outerballoon 727. Disposed between inner balloon layer 723 and outer balloonlayer 727 is an insulation layer 726.

Multi-layer balloon 720 can operate as a bipolar device where eachballoon portion 723 and 727 are separate poles. More specifically,insulation layer 726 allows conductive layer 721 of inner balloon layer723 and conductive portion 728 of outer balloon layer 727 to separatelyreceive RF energy and thereby define RF fields between adjacentconductive portions. For example, a given conductive portion 721 ofinner balloon portion 723 can act as one pole, and the two adjacentconduction portions 728 of outer balloon portion 727 can act as theother poles. Following this example, an RF field can be establishedbetween that conductive portion 721 of inner balloon portion 723 and oneof the adjacent conductive portions 728 of outer balloon portion 727,and a separate RF field be established between that conductive portion721 of inner balloon portion 723 and the remaining adjacent conductiveportion 728 of outer balloon portion 727.

FIG. 8 shows a cross-sectional view of a multi-layer balloon of aballoon catheter while in an expanded configuration, according to yetanother embodiment of the invention. Multi-layer balloon 800 includes aconductive layer 823, an insulation layer 822 and a conductive layer821. Conductive layer 821 and insulation layer 822 each have distinctsegments where the one segment of the insulation layer 822 is disposedbetween the conductive layer 823 and an associated segment of theconductive layer 821. Thus, conductive layer 823 includes portions 824,upon which insulation 822 and 821 are not disposed. Balloon catheter 900can operate as a bipolar device where conductive layer 823 acts as onepole and conductive layer 821 acts as another pole. Such a bipolardevice can produce an RF field between the conductive layers 823 and 821when energize by an RF generator (not shown in FIG. 8).

Although multi-layer balloon 800 is shown as having no material betweenadjacent segments of insulation layer 822 and conductive layer 821, inalternative embodiments, an insulation layer can be provided betweenthese adjacent segments of insulation layer and conductive layer. In yetanother alternative embodiment, an additional insulation layer can bedisposed on at least a portion of the conductive layer 821 and/orconductive layer 823.

FIG. 9 depicts a cross-sectional view of a balloon catheter having amulti-lumen catheter, according to yet another embodiment of theinvention. As shown in FIG. 9, balloon catheter 900 includes a catheter910 and balloon 920. Catheter 910 is a multi-layer catheter including anon-conductive layer 911, a conductive layer 912 and non-conductivelayer 913. Non-conductive layer 911 can define lumen 914, which is influid communication with the interior 925 of balloon 920. Conductivelayer 912 can be electrically coupled to the conductive material ofballoon 920 such that energy received from a RF generator (not shown inFIG. 9) can be provided to the conductive material of 920 via conductivelayer 912. Conductive layer 912 is thus an alternative to the conductiveelement 130 shown in FIG. 1 and conductive element 530 shown in FIG. 5.

The balloon catheter 900 shown in FIG. 9 can also include a guide wire930, which can be disposed within lumen 914 of catheter 910. Guide wire930 can be used to guide the balloon catheter to an appropriate positionwithin a patient's body such as, for example, a previously formed tissuecavity thereby disposing balloon catheter into a desired location.Although FIG. 9 depicts the balloon catheter 900 in the expandedconfiguration, guide wire 930 will typically be used while the ballooncatheter 900 is in a collapsed configuration.

FIG. 10 shows a cross-sectional view of a balloon catheter having amulti-lumen catheter, according to yet another embodiment of theinvention. Balloon catheter 1000 includes a multi-lumen catheter 1010and a balloon 1020. Multi-lumen catheter 1010 includes lumens 1012, 1014and 1016. Lumen 1012 can be used for example for a guide wire (not shownin FIG. 10). Lumens 1014 and 1016 can be used to allow the circulationof fluid within interior 1025 of balloon 1020. By controlling the rateat which fluid is introduced into and removed from interior 1025 ofballoon 1020, the size of balloon 1020 can be controlled while alsoallowing the fluid within interior 1025 to circulate. More particularly,by controlling the difference in the rates at which fluid is introducedinto and withdrawn from interior 1025, balloon 1020 can be changedbetween a collapsed configuration and an expanded configuration.Following the example shown in FIG. 10, lumen 1014 can be an input lumenby which fluid can be introduced into interior 1025 via outlet 1015.Lumen 1016 can be an output lumen through which fluid can be withdrawnfrom interior 1025 through outlet 1017.

This embodiment in which fluid can circulate within interior 1025 alsoallows a level of control in the manner by which tissue is ablated. Morespecifically, by allowing the circulation of fluid within interior 1025,the temperature of balloon 1020 can be, for example, reduced. Such areduction in the temperature of balloon 1020 allows the enhancement ofthe kill zone of the marginal tissue. Said another way, if the contacttemperature of the tissue surrounding balloon 1020 while in an expandedconfiguration increases too rapidly, the kill zone will be smaller thanif the temperature of the marginal tissue is increased at a slower rate.This allows a larger kill zone than would otherwise be the case. Thus,by controlling the circulation of fluid, the temperature of balloon 1020and therefore the temperature of the surrounding marginal tissue can becontrolled thereby allowing the selection of a desired kill zone.Alternatively, the temperature of balloon 120 can be increased,providing a thermal ablation mechanism for necrosis of the margin tissuein addition to the RF ablation mechanism.

FIG. 11 illustrates a cross-sectional view of a balloon catheter havingmultiple concentric balloons, according to an embodiment of theinvention. Balloon catheter 1100 includes multi-lumen catheter 1110 andmulti-layer balloon 1120. Multi-lumen catheter 1110 includes lumen 1112and lumen 1114. Multi-layer balloon 1120 includes an inner balloon 1123and an outer balloon 1127. Inner balloon 1123 defines an interior 1125.Interior 1129 is defined as the annular space between inner balloon 1123and outer balloon 1127. Lumen 1112 of multi-lumen catheter 1110 is influid communication with interior 1125 of inner balloon 1123. Similarly,lumen 1114 of multi-lumen catheter 1110 is in fluid communication withinterior 1129 of outer balloon 1127. Inner balloon 1123 and outerballoon 1127 can each be formed from a conductive material.

FIG. 12 depicts a partial cross-sectional view of a balloon catheterhaving multiple concentric balloons, according to another embodiment ofthe invention. As shown in FIG. 12, balloon 1220 includes an innerballoon 1223 and outer balloon 1227. Balloon 1220 can be connected to amulti-lumen catheter (not shown in FIG. 12) similar to multi-lumencatheter 1110 shown in FIG. 11. Outer balloon 1227 includes a set ofopenings 1228 through which fluid can pass. In addition, outer balloon1227 includes an irregular surface 1229, which provides separationbetween outer balloon 1227 and inner balloon 1223. This separationallows fluid to better pass between the inner balloon 1223 and outerballoon 1227, and exit the various openings 1228. FIG. 12 is notnecessarily shown to scale and, consequently, the openings 1228 can bemuch smaller, thereby allowing the fluid to pass through the openings1228 at a lower rate.

The fluid exiting openings 1228 can provide enhanced conductivity to themargin tissue surrounding balloon 1220. By providing enhancedconductivity, the ablation process can be modified. For example, when afluid having conductivity greater than the margin tissue exits openings1228, the margin tissue with the fluid has a greater conductivity thanwould be the case without the fluid. As a consequence, a greater amountof tissue can be ablated. In other words, tissue can be ablation to agreater depth (i.e., a greater distance from the balloon) because afluid being released into the margin produces an increased conductivity.

The fluid can be any type of fluid that provides increased conductivity.For example, the fluid can be a saline solution. Alternatively, thefluid can be a solution having ferric materials such as those describedin the co-pending patent application Ser. No. 10/665,110 entitled“Apparatus and Methods for Assisting Ablation of Tissue Using MagneticBeads,” filed on Sep. 16, 2003; which is incorporated herein byreference. Such a solution can have, for example, ferric particles witha size of 1-100 microns in diameter.

FIG. 13 depicts a side view of a balloon catheter having an atraumatictip, according to an embodiment of the invention. As shown in FIG. 32,balloon catheter 1300 includes catheter 1310, balloon 1320, andatraumatic tip 1350. Atraumatic tip 1350 can provide a blunt end to theballoon catheter 1300. Such a blunt end avoids the creation of anyfurther punctures or holes within the tissue of the patient while theballoon catheter is in the collapsed configuration and moved within thepatient. Although shown in connection with balloon catheter 1300, anatraumatic tip can be combined with any appropriate balloon cathetersuch as the above-described embodiments.

FIG. 14 depicts a block diagram of an ablation system having a ballooncatheter, according to an embodiment of the invention. As shown in FIG.14, balloon catheter system 1490 includes balloon catheter 1400, RFgenerator 1440, impedance measurement system 1450 and fluid regulator1460. Balloon catheter 1400 includes a catheter 1410, a balloon 1420 anda conductive element 1430. Although RF generator 1440, impedancemeasurement system 1450 and fluid regulator 1460 are shown in FIG. 14 inconnection with balloon catheter 1300, they can be used with any of theballoon catheters described above. In addition, impedance measurementsystem 1450 and fluid regulator 1460 are optional for any of theembodiments described herein.

RF generator 1440 is electrically coupled to conductive element 1430,which is electrically coupled to a conductive material of balloon 1420.Impedance measurement system 1450 can include a sensor (not shown inFIG. 14) disposed on an exterior balloon 1420. Such a sensor can allowthe measurement of the impedance of the tissue proximate to the exteriorof balloon 1420. The impedance of the tissue proximate to the exteriorof balloon 1420 provides an indication of the extent to which thattissue is destroyed through the ablation process. Based on the impedancemeasurement of the tissue proximate to the exterior of balloon 1420,impedance measurement system 1450 can provide a signal to RF generator1440. RF generator 1440 can control the amplitude, frequency, and/orpower of the RF energy provided to the conductive material of balloon1320 based on the signal received from impedance measurement system1450. In this manner, the ablation process can be monitored andcontrolled.

Fluid regulator 1360 can control the flow of fluid to the balloon 1420.For example, when balloon 1420 includes an outer balloon portion havingopenings (similar to the outer balloon portion 1227 shown in FIG. 12),fluid regulator 1360 can control the rate at which fluid exits theopening and is introduced to the margin tissue. For another example,when catheter 1410 is a multi-lumen catheter (similar to the multi-lumencatheter shown in FIG. 10), fluid regulator 1360 can control the rate atwhich fluid circulates within the interior of the balloon 1420.

FIG. 15 depicts a flowchart for making an ablation balloon, according toan embodiment of the invention. This process described in reference toFIG. 15 is similar to photolithography techniques used in theconstruction of integrated circuits. Although FIG. 15 describes aprocess for making many types of ablation balloons, for illustrativepurposes FIG. 15 will be described in reference to the balloon shown inFIG. 8 having a first conductive layer, segments of an insulation layerand segments of a second conductive layer.

At step 1500, a first portion of the balloon is masked based on a mask.Following the example of FIG. 8, the shape of the mask and the firstportion of the balloon corresponds to the portions 824 of conductivelayer 823 of balloon 820. At step 1510, an insulation layer on a secondportion of the balloon is deposited. In other words, the insulationlayer is disposed on the balloon excluding the masked portions of theballoon. At step 1520, a conductive layer on the second portion of theballoon is deposited. Following the example of FIG. 8, the conductivelayer 821 is disposed on the insulation layer 822 of balloon. At step1530, the mask is removed form the first portion of the balloon. As aresult, the first portion of the balloon is exposed as such portions 824of conductive layer 823 of balloon 800 shown in FIG. 8.

In alternative embodiments, a second insulation layer (not shown in FIG.8) can be deposited before the mask is removed. Once the mask isremoved, the conductive layer will be disposed between the firstinsulation layer and the second insulation layer. Such a secondinsulation layer can provide a protective layer over the conductivelayer.

In another alternative embodiment, a second insulation layer (not shownin FIG. 8) can be deposited on the first portion and the second portionof the balloon after the masked has been removed. Thus, once the mask isremoved, the second insulation layer will be disposed on the conductivelayer for the second portion of the balloon and on the first portion ofthe balloon. Such a second insulation layer can provide a protectivelayer over the entire balloon.

In one alternative embodiment, the balloon catheter can be used incombination with a radiation therapy device. For example, a radiationtherapy device having a balloon-like structure inflated with aradioactive fluid is in U.S. Pat. No. 6,083,148 to Williams, which isincorporated herein by reference. Such radiation therapy device isunderstood to operate more effectively when the balloon-like structureof the radiation therapy device has a more spherical shape in itsexpanded configuration. Accordingly, it is desirable for the tissuecavity formed by the removal of a tumor to have a more spherical shape.

An embodiment of the balloon catheter can be used to modify the shape ofthe tissue cavity formed by the removal of a tumor into a more sphericalshape before use of a radiation therapy device. More specifically, theballoon catheter disposed within the tissue cavity can be activated toablation the surrounding tissue thereby modifying the shape of thetissue cavity to a substantially spherical shape. The balloon cathetercan be removed and the radiation therapy device can be inserted into themodified tissue cavity. The radiation therapy device can then apply theradiation therapy.

Although some embodiments of the invention have been described above,for example, in connection with ablating margin tissue after a tumor hasbeen removed, some embodiments can be used in other applications. Forsuch other applications, the balloon can have an alternative shape andstructure as may be appropriate for that application. In other words,the particular shape and structure of the balloon can be selected tomatch the particular anatomy associated with a given application. Thevarious possible balloon structures include, for example, configurationswhere the balloon is compliant and configurations where the balloon hasenough rigidity that the balloon takes on a predefined shape whenexpanded. Alternatively, possible balloon structures include, forexample, configurations where the RF electrodes ablate surroundingtissue via direct contact, and configurations where the RF electrodesheat the fluid within the balloon and the tissue is ablated by theheated balloon. These various alternative applications and structuresare discussed below.

In one embodiment, for example, a balloon catheter can be used to treatprostatitis. For such an application, the balloon catheter can beinserted transurethrally and, when in the expanded configuration, theballoon can have an hour-glass shape to provide an improved positioningof the balloon about the prostate lobes. Once positioned and disposedwithin the expanded configuration, the RF electrodes can be electricallyactivated to an appropriate level to heat via direct contact.Alternatively, the RF electrodes can be electrically activated to anappropriate level to heat the fluid within the balloon such that theheated balloon can ablate the prostate lobes. Such an embodiment canalso be used to treat prostate cancer.

In another embodiment, a balloon catheter can be used for uterineablation. For such an application, the balloon in an expandedconfiguration can have a compliant structure that conforms to the shapeof the uterine when the balloon is filled with a fluid. In other words,the balloon can be positioned in the uterine cavity transvaginally,inflated into the expanded configuration by filling the balloon with afluid and then the RF electrodes can be electrically activated to ablatethe endometrial lining of the uterus. As discussed above, in analternative, the RF electrodes can be electrically activated to anappropriate level to heat the fluid within the balloon such that theheated balloon can ablate the endometrial lining of the uterus.

In yet another embodiment, the balloon catheter can be used to treatcervical cancer. For such an application, the balloon in an expandedconfiguration can have a compliant structure in a mushroom-like shape.FIG. 16 shows a cross-sectional view of a balloon catheter in anexpanded configuration, according to another embodiment of theinvention.

As shown in FIG. 16, balloon catheter 1600 includes catheter 1610 andballoon 1620. Balloon 1620 has a compliant structure that when in anexpanded configuration has a mushroom-like shape. Balloon 1620 includesballoon portions 1622 and balloon portion 1624, which are suitable forplacement within and surrounding the cervix. More specifically, balloonportion 1624 can be disposed within and through the os; balloon portions1622 can be disposed about and envelope the cervix. Balloon catheter1600 can be dimensioned, for example, as a 5 to 7 French distal balloonshape by 3 cm that expands to a concave portion approximately 4 to 6 cmin diameter.

Similar to the discussion above, once positioned, the balloon here canbe inflated into the expanded configuration by filling the balloon witha fluid and then the RF electrodes can be electrically activated toablate the endometrial lining of the uterus. Alternatively, the RFelectrodes can be electrically activated to an appropriate level to heatthe fluid within the balloon such that the heated balloon can ablate thecervix.

CONCLUSION

While various embodiments of the invention have been described above, itshould be understood that they have been presented by way of exampleonly, and not limitation. Thus, the breadth and scope of the inventionshould not be limited by any of the above-described embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

The previous description of the embodiments is provided to enable anyperson skilled in the art to make or use the invention. While theinvention has been particularly shown and described with reference toembodiments thereof, it will be understood by those skilled in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope of the invention.

1. An apparatus, comprising a catheter having a lumen; a conductiveelement disposed along the catheter; and a balloon having an interior influid communication with the lumen of the catheter, the balloon having afirst layer formed at least in part of a conductive materialconductively coupled to the conductive element, the balloon having acollapsed configuration and an expanded configuration, at least aportion of the balloon including a second layer and a third layer, thesecond layer being formed of an insulation material, the third layerbeing formed at least in part of a conductive material.
 2. The apparatusof claim 1, wherein: the conductive material of the first layer of theballoon includes a plurality of conductive portions, two adjacentconductive portions from the plurality of conductive portions beingseparated by an insulation portion from a plurality of insulationportions.
 3. The apparatus of claim 1, wherein: the first layer of theballoon includes a plurality of conductive portions, two adjacentconductive portions from the plurality of conductive portions of thefirst layer of the balloon being separated by an insulation portion froma plurality of insulation portions, the third layer of the balloonincludes a plurality of conductive portions, two adjacent conductiveportions from the plurality of conductive portions of the third layer ofthe balloon being separated by an insulation portion from a plurality ofinsulation portions, each conductive portion from the plurality ofconductive portions of the first layer of the balloon being offset froma corresponding conductive portion from the plurality of conductiveportions of the third layer of the balloon.
 4. The apparatus of claim 1,further comprising: the first layer and the third layer of the ballooneach being a bipolar electrode.
 5. The apparatus of claim 1, furthercomprising: an atraumatic tip disposed at a distal end of the balloon.6. The apparatus of claim 1, further comprising: a guide wire disposedwithin the lumen of the catheter and an interior of the balloon.
 7. Theapparatus of claim 1, wherein the balloon is configured to be disposedwithin a tissue cavity previously-formed by removal of a tissue mass andconfigured to expand to a size associated with the tissue cavity toablate margin tissue associated with the tissue cavity.
 8. A method foroperating a catheter having a balloon in communication with thecatheter, comprising: percutaneously disposing the balloon while in acollapsed configuration into a tissue cavity previously-formed byremoval of a tissue mass, the balloon being formed of a conductivematerial; expanding the balloon into an expanded configuration, theballoon in the expanded configuration having a shape associated with ashape of the previously-formed tissue cavity; and applying aradio-frequency signal to the conductive portion of the balloon.
 9. Themethod of claim 8, further comprising: circulating a fluid within theballoon, the fluid within the balloon having a temperature less than atemperature of the conductive material of the balloon.
 10. The method ofclaim 8, the balloon being a first balloon, the catheter including asecond balloon disposed outside the first balloon and being fluidpermeable, further comprising: providing a fluid within a secondballoon.
 11. The method of claim 8, the balloon being a first balloon,the catheter including a second balloon disposed outside the firstballoon and being fluid permeable, further comprising: providing a fluidwithin a second balloon based on an impedance associated with the tissuecavity.
 12. The method of claim 8, the applying including modifying theshape of the previously-formed tissue cavity into a substantiallyspherical shape, the method further comprising: removing the balloonfrom the modified tissue cavity; inserting a radiation therapy deviceinto the modified tissue cavity; and performing radiation therapy basedon the radiation therapy device.
 13. The method of claim 8, wherein theapplying includes applying the radio-frequency signal to the conductiveportion of the balloon such that heat from the conductive portion of theballoon is produced to ablate at least a portion of a margin tissueassociated with the tissue cavity.
 14. A apparatus for treating a margintissue associated with a tissue cavity after removal of a tissue mass,comprising: a tubular member defining a lumen; and a balloon having atleast one electrode and defining an interior in fluid communication withthe lumen of the tubular member, the balloon having a range ofconfigurations including an expanded configuration corresponding to thetissue cavity and a collapsed configuration, the at least one electrodebeing disposed within a first layer of balloon, the balloon furtherincluding a second layer and a third layer, the second layer of theballoon being formed of an insulation material, the third layer of theballoon being formed of its own at least one electrode.
 15. Theapparatus of claim 14, wherein: the at least one electrode of theballoon is formed with the first layer of the balloon.
 16. The apparatusof claim 14, further comprising: a radio-frequency generator coupled tothe at least one electrode of the first layer of the balloon and the atleast one electrode of the third layer of the balloon, the first layerof the balloon and the third layer of the balloon defining a bipolarconfiguration.
 17. The apparatus of claim 14, wherein the at least oneelectrode of the balloon includes a first conductive portion and asecond conductive portion separated by an insulation portion from aplurality of insulation portions.